The R1276S from Ricoh Electronic Devices is a 36-V rated synchronous step-down dc-dc converter with built-in transistor. Under cranking condition, the switching frequency is automatically reduced to keep output voltage level constant. This is a high-reliability semiconductor device for industrial application (-Y) that has passed both the screening at high temperature and the reliability test with extended hours. The R1276 family also includes devices that satisfy the needs of consumer and automotive environments.
This dc-dc converter features an efficiency of 95%. It maintains the output voltage constant at cranking by reducing a switching frequency to the minimum 1/4. And it achieves the EMI noise reduction by using a spread spectrum clock generator. (Diffusion Rate: +10%).
The R1276S is designed for use in FA Equipment, Smart Meters; Surveillance Cameras and Vending Machines that are used outside or under high-temperature conditions; and Motors and Lightings that are accompanied by self-heating.
Summary of key specifications:
- Input Voltage Range (Maximum Rating): 3.6V to 30V (36V)
- Start-up Voltage: 4.5V
- Standby Current: Typ. 4µA
- Output Voltage Range: 0.7V to 6.5V
- Feedback Voltage: 0.64V ±1.0%
- Consumption Current at No Load (at VFM mode): Typ. 12µA
- Adjustable Oscillator Frequency Using External Resistors: 250kHz to 1MHz
- External Synchronous Clock Frequency: 250kHz to 1MHz
- Spread Spectrum Clock Generator (SSCG): Diffusion Rate Typ. +10%
- Minimum ON-Time: Typ. 70ns
- Minimum OFF-Time: Typ. 120ns
- Duty-over: Min. 1/4
- Thermal Shutdown: Tj = 160°C
- Undervoltage Lockout (UVLO): VCC = 3.3V (Typ.)
- Overvoltage Lockout (OVLO): VIN = 35V (Typ.)
- Overvoltage Detection (OVD): FB Pin Voltage (VFB) +10%
- LX Current Limiting: Typ. 4.2A
- Over-current Protection: Hiccup-type
- High-side Transistor ON Resistance: Typ. 0.110Ω
- Low-side Transistor ON Resistance: Typ. 0.045Ω